What is the context window of StepFun: Step 3.5 Flash?

StepFun: Step 3.5 Flash supports a context window of 262K tokens.

Is StepFun: Step 3.5 Flash free to use?

StepFun: Step 3.5 Flash is a paid model. It costs $0.100 per million input tokens and $0.300 per million output tokens.

How is LLM API pricing calculated?

LLM pricing has two components: input tokens (everything you send) and output tokens (what the model generates). Total cost = (prompt tokens × input rate + output tokens × output rate) / 1,000,000 × number of requests.

StepFun: Step 3.5 Flash API Pricing — $0.100 Input / $0.300 Output per 1M Tokens

Q: How much does StepFun: Step 3.5 Flash cost?

StepFun: Step 3.5 Flash costs $0.100 per million input tokens and $0.300 per million output tokens via OpenRouter. Pricing was last updated Oct 29, 2026.

StepFun: Step 3.5 Flash by Stepfun — $0.100 input / $0.300 output per 1M tokens via OpenRouter. Context: 262K tokens. Pricing last updated Oct 29, 2026.

Input / 1M tokens

$0.100

Output / 1M tokens

$0.300

Provider

Stepfun

Context window

262K tokens

Via

OpenRouter

Cost at common usage volumes

Usage	Daily	Monthly
Chatbot (100/day)	$0.042	$1.27
Small app (1K/day)	$0.250	$7.50
Mid-scale (10K/day)	$3.50	$105.00
Large scale (100K/day)	$80.00	$2400.00

Model ID: stepfun/step-3.5-flash
Data source: OpenRouter public API — updated Oct 29, 2026.

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About StepFun: Step 3.5 Flash

StepFun: Step 3.5 Flash is an LLM developed by Stepfun. Input costs $0.100 per million tokens and output costs $0.300 per million tokens via OpenRouter. It supports a context window of 262K tokens.

Pricing Details

Via the OpenRouter API:

Input tokens: $0.100 per 1 million tokens
Output tokens: $0.300 per 1 million tokens

A token is roughly 0.75 words. For context: a typical user message of 100 words is approximately 133 tokens; a 500-word system prompt is about 650 tokens.

How Much Does StepFun: Step 3.5 Flash Cost?

For a typical chatbot application (1,000 requests/day, 1,000 prompt tokens and 500 output tokens per request):

Daily cost: $0.2500
Monthly cost: $7.500

Accessing StepFun: Step 3.5 Flash via OpenRouter

OpenRouter provides a unified API for 200+ LLMs including StepFun: Step 3.5 Flash. You can use it with any OpenAI-compatible SDK by setting the base URL to https://openrouter.ai/api/v1 and using your OpenRouter API key. The model ID is stepfun/step-3.5-flash.

Compare StepFun: Step 3.5 Flash with Other Models

Use the AI Model Cost Comparison tool to compare StepFun: Step 3.5 Flash against GPT-4o, Claude 3.5 Sonnet, Gemini 1.5 Pro, or any other model side by side. Or use the LLM API Cost Calculator to browse all 456+ models sorted by cost for your specific usage.

Frequently Asked Questions

Yes. StepFun: Step 3.5 Flash is available on OpenRouter with the model ID stepfun/step-3.5-flash. OpenRouter provides a unified API compatible with OpenAI's SDK format.